Lovely flowers on convolulus plant, they may look beautiful but the plant grows madly and scrambles over other plants. It entwines and strangles them. The stems grow long distances and the plant can smother a garden. I saw these at Bovisand Bay in Devon. The fly on them gives an idea of their scale. The leaves are heart shaped and block out the light to underlying plants. If you get it in your garden it takes a lot of work to remove it. If you leave a tiny bit of its white roots in the soil a whole new plant will grow from it.